Case Report: Renal sarcoidosis coexisting with membranous and IgA nephropathy, a very uncommon association

Sarcoidosis is a multisystemic inflammatory disease of unknown etiology with more frequent lung and lymph node involvement. Despite kidney involvement occurring between 25% and 43%, it may be underdiagnosed, with interstitial granulomatous nephritis and nephrocalcinosis being the most common features, and glomerular disease being less frequent.

A 43-year-old man came to the emergency room (ER) because of macroscopic hematuria, arthralgias, pitting inferior extremities edema, asthenia, and dry cough without dyspnea. Evaluation revealed nephrotic range proteinuria and glomerular hematuria, suggesting an impure nephrotic syndrome. The kidney biopsy showed features of membranous nephropathy and granulomatous interstitial nephritis, with immunofluorescence showing codominant mesangial immunoglobulin A (IgA) and immunoglobulin G (IgG) deposits.

Steroids plus angiotensin receptor blocker (ARB) antagonists were effective, with symptoms subsiding and proteinuria level decreasing after 8 months of follow-up.